One possible reason could be a difference in their goals. Naruto is from the Hidden Leaf Village with a mission to protect it and promote peace there. Rias, on the other hand, has her own responsibilities in the Underworld. Their conflicting duties might lead to Naruto leaving.
One possible reason could be that Naruto feels he has learned all he can from Jiraiya at that point. Maybe he wants to explore his own path independently and test his skills without Jiraiya's constant guidance.
It could start with Naruto getting a mysterious message or a vision that tells him he and Sasuke need to leave together for the greater good. He then goes to find Sasuke and convinces him to come along.
It can create a sense of growth for Naruto. Without Jiraiya by his side, he has to rely more on his own instincts and the skills he has already acquired. This can lead to new character development as he faces challenges alone.
Well, it can add a lot of drama to the plot. For starters, it could lead to a reconciliation arc between Hinata and Naruto. Their relationship would be in a state of flux, with Naruto perhaps being initially hesitant to forgive or trust her again. This would create tension and anticipation for the readers. Also, Hinata's regret might make her more determined to make amends, which could lead to her taking bold actions to get back into Naruto's good graces and the story's main events.
One possible reason could be that she realizes she truly loves Naruto too much to be apart from him. Maybe she left because of some misunderstanding or external pressure, but then comes to understand that her place is by his side. Another reason might be that she sees how much Naruto has grown and changed, and regrets not being there to support him during that journey. Also, she could have found that life without Naruto is just not as fulfilling as she thought it would be.
One possible plotline could be that Naruto discovers some long - lost secret about his mother Kushina and decides to leave the village with her to explore this mystery further. Maybe they are on a quest to find some hidden power or knowledge that is related to Kushina's Uzumaki heritage.
It could also be due to a power struggle. Naruto is extremely powerful and independent. If Rias or other members of the peerage try to control or limit his power in some way, he would not tolerate it. His power is a part of who he is, and he's used to using it freely to protect others. So this could lead to his departure from the peerage.
One possible plotline could be that Naruto leaves with Tsunade on a mission to find a rare herb that is said to have the power to heal any wound. Along the way, they face various enemies who also want the herb for their own malicious purposes. Naruto's skills and Tsunade's wisdom would be put to the test as they battle their way through.
The villagers would be worried at first. Naruto is a hero to them, and Tsunade is their respected leader. Their sudden departure would cause a stir. Some might think that there is a great danger approaching that they are going to face alone. There could be a lot of speculation and unease in the village.